Apparatus for protecting surfaces from ice formation



May 14, 1940-. E. F. FIELD 2.200.838

APPARATUS FORPROTEGTING SURFACES FROM ICE FORMATION Filed Nov. 13, 1937 2 Sheets-Sheet 1 May l4, 1940. I E. F. FIELD 2.200.838

APPARATUS FOR PROTECTING SURFACES FROM ICE FORMATiON Filed Nov. 13, 1937 2 Sheets-Sheet 2 fwmmfor craft.

Patented Mi, 14, 1940 PATENT OFFICE APPARATUS FOR PROTECTING SURFACES ICE FORMATION Edgar Fuller Field, Sutton Coldiield, England, assignor to Dunlop Rubber Company. Limited, London, England,'a British company Application November 13, 1937, Serlal No. 174.301 In Great Britain November 24, 1936 12 Claims.

This invention concerns improved means for protecting surfaces from ice formation and in particular concerns improved means for preventing the formation of ice upon the surfaces of air- Permeabl'e coverings for such surfaces have already. been proposed, such coverings being fed on the under side by contact with apertures or wicks in a supply tube or channel fed with a liquid capable of lowering the freezing point of be protected, and a rapid and uniform replenishment of the ice preventing liquid which is carried away by the air during flight.

This rapid saturation is readily attained by I the present invention, in view of the intimate initial contact and penetration of the liquid, not only into the actual material of which the supply channels conducting the liquid are constructed, but also into the remainder of the covering fed by the channels.

In my invention, the ice preventing liquid is rapidly absorbed by the whole length of the wall of each channel, and the liquid percolates out simultaneously therefrom to the area to be protected through a very large number of adjacent and individually conductive paths.

This improved capacity for intensive absorption and percolation per unit length of channel permits the use of a comparatively low feed pressure for initial saturation, and a'still lower pressure to maintain saturation during flight.

It will be evident that the nature of the material lends itself readily to economy and to umformity of manufacture and replacement and in itspreferred form can be assembled upon the leading edge of an existing wing without any which ice-preventing liquid is diffused to the'outen surface of the covering comprises a strip or strips of absorbent textile fabric positioned beneath the 55 said covering and forming one or more channels extending across portions of the threads of the said strip or strips which channels and the threads extending therefrom serve to conduct and to distribute liquid to the said covering.

Preferably, portions of the thread which form 6 the supply channels extend integrally also toor towards the edges of the strip in an upward or downward direction while the channels extend substantially horizontally along the leading edge of the wing or strut.

The various features of my invention are illustrated by way of example in the accompanying drawings, in which- Fig. 1 is a plan view of a portion of a channel forming strip prior to the formation of a channel 15 embodying my invention; Fig. 2 is a sectional elevation of the strip of Fig. 1; Figs. 3, 4 and 5 are side elevations of the strip folded to form a channel; Figs. 6 and 9 are cross-sections showing two embodiments of the leading edge of the wing of m an aircraft to which folded strips are secured: Figs. 7, 8 and Figs. 10 and 11 are part sectional views of strips incorporating alternative forms of supply channels; Fig. 12 is a front elevation of a section of an assembly embodying a preferred gs form of the invention; Fig. 13 is a vertical section of the assembly of Fig. 12.

As shown in Fig. 1, a strip l of absorbent fabric, such as bleached duck of a suitable width W, is folded at 2, Figs. 3 to 5, and the contacting 30 faces of the folds 2 coated with a suitable adhesive along narrow width lines 4 are secured together by stiches 5, thereby forming a supply channel I, the walls of which are integralwith the free edge portions 3. 5

' A part'or parts of the channel portion 8 are preferably coated with a narrow impermeable 'band or hands of rubber or rubber coated fabric 6 which may be subsequently vulcanized thereto for the purpose of confining the outward diifu- 49 sion of the liquid substantially to the vicinity of the junction formed by the adhesive and/or stitches As-shown in Fig. 6, the supply channel I is seated in a groove l formed in the surface of 45 the leading edge I and the free edges 3 when pulled apart from the position shown in Figs. 4

and 5, are secured to the surface of the leadingedge on either side of the channel I by suitable adhesive- 50 The surface of the leading edge itself may be protected by .a foundation layer of unvulcanized rubberized fabric impervious to the ice preventing liquid which may be ethylene glycol, such a layer being shown at ",Flgs. 12, 13. 7

Several such tubular supply channels may be formed parallel to one another from a plurality of parallel folds or at suitably converging angles and the supply channels may be graduated in length or section to vary the supply of liquid in accordance with the taper of the wing from its root adjacent the fuselage to its outer end or tip.

In the modifications shown in Figs. '7, 8, 10 and 11, a plurality of component fabric strips are employed, the edges of which overlap one another to form the supply channels. For example, each one of the supply channels shown in Figs. 7 and 8 isformed by a pair of component fabric strips in which the free edge of one strip la is overlapped when lying fiat to a depth of about one and a half to two inches by a portion of another strip lb adjacent to it. The overlapping portion of the adjacent strip lb is not laid flat upon the first strip la but is formed of greater width at lc so that, when the overlapping edges are secured together by stitches and/or adhesive, a broad tube or channel of flattened section is produced when the composite strip is lightly stretched in position on the wing structure.

As shown in Figs. 7 and 8, portions of the threads of each one of the strips la and lb from an integral part of one supply channel 8, and extend integrally away from it on one side, and the threads of the other strip also form a part of the same channel and extend away from it to form part of an adjacent channel, if desired.

The modification shown in Fig. 9 permits the device to be assembled upon the leading edge of the wing of an aircraft without the necessity for providing grooves in the surface of the leading edge.

As shown in Fig. 9, a base member I l is secured to the leading edge 1, theunder surface of the member ll being preferably formed with a plurality of grooves l2 serving to reduce the weight of the member and to promote sufficient flexibility to make it adaptable to the profile of the leading edge.

The base member ll may be made or moulded from any suitable lightweight material, for example, cork, and of such a cross-section that the streamline profile is unimpaired.

A groove I3 is formed or moulded in the outer surface of the base II and is reinforced with a fabric strip l4, which may be rubberized.

A fabric strip l extending across the surface to be protected is secured to the base member I l by stitches 5 and/or adhesive, and the portion of the strip forming the outer surface of the supply channel 8 is covered by an impermeable band 6. promoting the flow of liquid laterally through the threads towards the edges 3.

When the strip and its integral supply channel 8 is positioned, as shown in Fig. 6 or 9, the fabric constituting the rear portion of the channel seated in each groove is comparatively free from tension and subsequently permits an unrestricted flow of liquid.

In the modification shown in Fig. 10, the free edges 3 extending away from the folded portion 2 .of the strip l are not coterminous with one another, but are superposed and separated from, one another by an interposed strip ll] of narsupply channel 8 and extends from the free edge 3 on one side to the free edge 3 on the other side, and upon the broad strip l are positioned two strips Id and Ie, the adjacent edges of which are spaced apart to constitute the supply channel 8, which is completed by a further strip If partly overlapping the adjacent edges of the strips Id and le and by nonpermeable bands 6 above and below the channel 8.

The construction shown. in Fig. 11 is particularly advantageous by reason of its conforming as nearly as possible to a streamline form.

If desired, the strips may be composed of bias cut fabric, so that the threads extend at an angle from the walls of the channels.

In the preferred assembly, as shown in'Figs. 12 and 13, a foundationlayer 22 is secured to the surface of the leading edge I and upon this is positioned a vulcanized rubber sheet l5, the surface of which is embossed, or formed with other minor projections and indentations, which serve to spread the fiow of ice-preventing liquid.

Adjacent the centre line of the leading edge is positioned the folded strip or strips l formed with the supply channel 8, into which liquid is fed from a feed pipe l6.

Positioned upon the fabric strip or strips I incorporating the supply channel 8 is a covering ll of permeable material, such as leather serving as an additional spreading and diffusing member.

As shown in section in Fig. 13, the marginal 1 turned inwards at l9 and secured in contact with the impermeable foundation layer 22, so that the edges of the said marginal portions abut the edges of the embossed rubber sheet l5 and form therewith a shallow curvilinear space 20 supplied with liquid from the supply channel 8.

The yielding surface of the permeable leather covering ll 'is maintained in streamline contour and is protected from abrasion due to the air stream by an outer permeable covering l8, which consists of a rubber sheet vulcanized to an inextensible backing, both sheet and backing being perforated with a plurality of fine apertures 23.

Fairing elements also of leather may be positioned at 2| to ensure the preservation of the streamline contour of the marginal portion of the outer permeable covering l8.

It is to be particularly understood that Fig. 13 is diagrammatic insofar as the various parts, for clearness, are shown more widely spaced and of greater thickness than obtains in the final assembly.

For example, the overall thickness of the supply channel 8 is of the order of one sixteenth of an inch between the outer surfaces of the impermeable bands 6.

In consequence, when the coverings l1 and I8 are tensioned in position, the inner face of the,

' a suitable pump immediately saturates all the threads of the strip or strips of fabric in which the channel or channels 8 are incorporated and saturates that portion of the permeable leather covering in contact with the channel or channels, any excess liquid filling the space 28 and diffusing rapidly through the remainder of the permeable leather covering and through the apertures in the outer permeable covering l8.

Having now particularly described my invention, I claim 1. Means for protecting aircraft from ice formation which comprises a permeable covering positioned on the surface of the structure to be protected through which ice preventing liquid is difiused to the outer surface of the covering, a conduit extending beneath said .covering and having a wall comprising a strip of absorbent textile fabric, the threads of said strip extending outwardly from said conduit, which conduit and the threads extending therefrom serve to conduct and to distribute liquid to the said covering.

2. Apparatus for protecting aircraft surfaces from formation of ice which comprises a flexible base of streamlined section having a groove, a conduit in said groove, said conduit having walls comprising a strip of fabric having threads extending from said channel outwardly over said base and a covering on said conduit and base to distribute the fluid therefrom.

3. Apparatus for protecting the leading edge of an air-plane wing against accumulations of ice which comprises a distributing sheet permeable to an ice preventing liquid secured to the leading edge of said wing to form a narrow space therebetween, a conduit extending lengthwise of said leading edge comprising a strip offabric coated with an impermeable material and permitting liquid to pass from said conduit lengthwise of said fabric, an embossed flexible base on said leading edge and supporting said conduit. I

4. Means for protecting aircraft from ice formation which comprises a permeable covering positioned on the surface of the structure to be protected through which ice preventing liquid is diffused to the outer surface of the covering, a conduit positioned beneath said covering and having a wall comprising a strip of absorbent textile fabric the threads of said strip extending outwardly from said conduit, said conduit and the threads extending therefrom serving to conduct and to distribute liquid to said covering, and a protective covering on said permeable covering and having a plurality of apertures therein.

5. Means for protecting aircraft from ice formation which comprises a .permeable covering positioned on the surface of the structure to be protected through which ice preventing liquid is diffused to the outer surface of the covering, a conduit positioned beneath said covering and having a wall comprising a strip of. absorbent textilefabric the threads of said strip extending outwardly from said conduit, said conduit and the threads extending therefrom serving to conduct and distribute liquid to said covering and a channel of impermeable material partly encasing said strips.

6. Means for protecting aircraft from ice formation which comprises a permeable covering positioned on the surface of .the structure to be protected through which ice preventing liquid is diffused to the outer surface of the covering, a conduit formed by overlapping edges of adjacent strips of absorbent fabric positioned beneath said covering, the threads of said strips extending outwardly from said conduit, said conduit and threads serving to conduct and distribute liquid to said covering.

7. Means for protecting aircraft from ice formation which comprises a permeable covering positioned on the surface of the structure to be protected through which ice preventing liquid is diffused to the outer surface of the covering, a conduit formed by the overlapping edges .of adjacent strips of absorbent fabric in which one side of the conduit formed by the said overlapping edges is of greater width than that side of the same conduit formed in the other strip with threads of said strip extending outwardly from said conduit, said conduit and the threads extending therefrom serving to conduct and distribute liquid to saidcovering.

8. Means for protecting aircraft from ice formation which comprises a permeable coverin positioned on the surface of the structure to be protected through which ice preventing liquid is diffused to the outer surface of the covering, a conduit positioned beneath said covering and having a wall comprising a strip of absorbent textile fabric having threads extending at a substantial angle to said conduit and outwardly from said conduit, said conduit and threads extending therefrom serving to conduct and to distribute liquid to said covering.

9. A conduit for conveying and distributing an ice preventing fluid which comprises a, conduit which is formed of a permeable fabric folded double and stitched parallel to the edge of the fold thus formed and at a short distance therefrom to form part of a conduit and having threads permeable to said fluid and extending away from said conduit whereby fluid may penetrate from said conduit through said threads and serve to conduct and to distribute liquid to said covering.

10. A conduit for conveying and distributing an ice preventing fluid which comprises a pair of overlapping fabrics stitched on parallel lines to form a part of a conduit and having threads permeable to said fluid and extending away from said conduit whereby fluid may penetrate through said threads and an impermeable material covering sa-id overlapping fabrics to permit seepage of fluid only through said stitched parts.

11. A conduit for conveying and distributing an ice preventing fluid which comprises a base fabric, a strip of fabric stitched in spaced parallel lines to said base fabric to form a conduit and having threads permeable to said fluid extending away from said conduit whereby fluid may penetrate from said conduit to said threads, the walls of said conduit being exteriorly coated with an impermeable material whereby liquid mayl seep therefrom only through the stitched portions of said fabric.

from formation of ice which comprises a conduit for conveying and distributing an ice preventing fluid and having a longitudinally extending slot, a fabric forming a part of the conduit and permeable to said fluid and extending through said slot outwardly beyond the outer surface of said conduit whereby fluid may penetrate'from said conduit through said outwardly extending part of said fabric.

EDGAR FULLER FIELD. 

